Liquid filter



FIG. 1 is a side view with the broken line illustration of each end fitting and wrench seating surface, and a central region of the design not included as part of the design sought to be patented the other sides being identical; and,

FIG. 2 is an end view with the broken line illustration of the end fitting and wrench seating surface not part of the design sought to be patented the other end being identical. 

The ornamental design for a liquid filter, as shown and described. 